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NMR investigation of biodegradable polyesters for medical applications
Authors:Janusz Kasperczyk
Abstract:Results of NMR studies of chain microstructure in polylactide, poly(lactide‐co‐ϵ‐caprolactone), poly(lactide‐co‐glycolide) and poly(glycolide‐ϵ‐caprolactone) are presented. The appropriate conditions of polymerization: temperature, solvents, type of initiators allows moulding of the structure of obtained polyesters. Statistical analysis of growing chains helps to identify in NMR spectra signals of the random and block segments of copolyester chains. Precise control of reaction conditions allows modification of chain structures by affecting rates of transesterification. Equations allowing for quantitative determination of the role of transesterification reactions on the basis of intensities of NMR resonance lines are given. Changes in the microstructure of macromolecular chains were determined using calculated values of transesterification coefficients, degree of randomness and values of average lengths of syndiotactic or isotactic blocks in lactide homopolymers or average lengths of comonomer units in copolymers.
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